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SUMMARY:Quantum Entanglement of Bethe States
DTSTART;VALUE=DATE-TIME:20260707T030000Z
DTEND;VALUE=DATE-TIME:20260707T050000Z
DTSTAMP;VALUE=DATE-TIME:20260704T022800Z
UID:indico-event-5154@indico-tdli.sjtu.edu.cn
DESCRIPTION:Speakers: Deliang Zhong（钟德亮） (Institute of Theoretic
 al Physics\, Chinese Academy of Sciences)\n\nAbstract:We investigate the q
 uantum entanglement of Bethe states across a family of integrable spin cha
 ins\, including the XXX$_{\\frac{1}{2}}$ model\, its higher-spin generaliz
 ations (XXX$_s$)\, and the non-compact $SL(2\,\\mathbb{R})$ chain. For on-
 shell eigenstates\, we perform a comprehensive scan of the bipartite entan
 glement entropy across the entire spectrum of finite chains with periodic 
 boundary conditions\, and identify the Bethe solutions that minimize and m
 aximize the entanglement. These extremal solutions follow systematic\, spi
 n-dependent patterns in the Bethe quantum numbers. In the XXX$_{\\frac{1}{
 2}}$ spin chain\, for the antiferromagnetic chain\, the state with minimal
  entropy always coincides with the lowest-energy state (the ground state) 
 within a given fixed-magnon sector. For the higher-spin XXX$_s$ model\, ho
 wever\, the lowest-entropy state is not always identical to the ground sta
 te\, and can even be the state of highest energy. By contrast\, the Bethe 
 roots that maximize entropy exhibit considerably more intricate structure.
  Our analysis further reveals how special Bethe root configurations\, such
  as singular and strange solutions\, affect entanglement\, and it uncovers
  characteristic entanglement features in the non-compact $SL(2\,\\mathbb{R
 })$ chain that are absent from compact spin chains. For off-shell Bethe st
 ates\, we develop an optimization algorithm that extremizes the entangleme
 nt entropy over rapidity distributions\, enabling us to explore the maximu
 m entanglement achievable by a Bethe state without imposing the Bethe ansa
 tz equations.Biography:Deliang Zhong received his bachelor’s degree from
  Peking University in 2014 and his Ph.D. from Ecole Normale Supérieure in
  Paris\, France\, in 2019. He was a postdoctoral researcher at Tel Aviv Un
 iversity\, Israel\, from 2019 to 2023\, and at Imperial College London\, U
 K\, from 2023 to 2026. He is currently an Associate Researcher at the Inst
 itute of Theoretical Physics\, Chinese Academy of Sciences.Alternative onl
 ine link: https://meeting.tencent.com/dm/HFMdcR9w7UxuID: 767893024 (No 
 Password)\n\nhttps://indico-tdli.sjtu.edu.cn/event/5154/
LOCATION:Tsung-Dao Lee Institute/N6F-N600 - Lecture Room (Tsung-Dao Lee In
 stitute)
URL:https://indico-tdli.sjtu.edu.cn/event/5154/
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